Defective Solar Cell - Image Courtesy of Fluke Corp 2010

Here is a infrared image, with Fluke IR-Fusion™ technology "blending" taken by a colleague of my in Spain...Roberto Poyato. If you adjust the level and span properly, and make sure that you are not getting thermal reflections off of the surfaces, you can often determine defective or under-performing PV cells within a panel. The one in the center of this image stuck out like a sore thumb in infrared! It was verified from the back side of the panel as well.